Rotary embossing systems have traditionally been used to emboss the webs that form absorbent articles. Typical embossing systems have included rotary embossing rolls and cooperating, rotary anvil rolls. Different embossment dies can be fixed to rotary embossing rolls to produce a variety of desired embossment regions for absorbent articles.
A typical embossed absorbent article, such as feminine sanitary napkin comprises a topsheet, absorbent core and backsheet, the backsheet is usually attached to the top sheet prior to the embossment of the topsheet and absorbent core. The attachment of the backsheet to the absorbent core prior to embossment has limited the depth of the embossment regions, as if the embossment is too deep the backsheet may be damaged during the embossment process, such as by cutting or tearing the backsheet. The backsheet is typically made of a water resistant material, such as plastic, which makes the backsheet more vulnerable to damage, than for example a non-woven web. In addition to harming the appearance of the absorbent article, damage to the backsheet can compromise the effectiveness of the absorbent article, as a damaged backsheet could allow absorbed fluids to leave the absorbent article and contact the skin or clothes of a wearer. It has also been difficult to emboss an absorbent article to a uniform depth along the entire embossment region. This is especially true when the embossment region has one or more closed ends, for example embossment regions in the shape of a peanut or oval. The separation distance between the embossing roll and rotary anvil roll increases at the ends of the ends of the embossment regions resulting in less pressure being allied by the embossing dies, and a corresponding reduction in depth in the embossment regions. The lack of pressure is increased when the ends of the embossment region are closed, as the pressure is spread out along an even greater surface area.
Deep channel embossments in an absorbent article provide improved fit of the absorbent article to the wearer's body, which is important in delivering superior protection performance. Deep channel embossments also provide a pleasant feminine design to the wearer. Further the embossed region also serves as a fluid barrier that prevents fluid from running off to the side of the absorbent article.
In addition, the process of forming deep channel embossments can produce embossment regions, not only in the surface contacted by the rotary embossing rolls (typically the body facing surface including the topsheet), but also in the opposing surface (typically the garment facing surface). The garment facing surface of the absorbent core is the surface that will come in contact with the backsheet. The backsheet will often conform to the embossments present in the garment facing surface of the absorbent core, resulting in an uneven surface in the backsheet. The uneven surface of the backsheet causes problems when trying to attach release paper to the surface of the backsheet. Adhesive is usually applied to the release paper first and then the release paper is contacted with the backsheet, such that the adhesive holds the release paper to the backsheet until use. However, as there are valleys present in the backsheet due to the embossments the adhesive present on the release paper will bridge these valleys, and consequently the adhesive will not come into direct contact with the backsheet. The irregular adhesive contact leads to several problems, including poor adhesive transfer from the release paper to the backsheet allowing adhesive to remain on the release paper or reducing its effectiveness of remaining on the absorbent article and transferring to an undesired surface, such as a user's panties. Another problem is that when users peels the release paper off the pads, the adhesive strings (situation similar to gum sticking/string to your shoe when you step on gum and lift your foot) between the backsheet and release paper. The adhesive could get to a user's finger and snap back to either release paper or backsheet. These are all undesired usage experience for the users. A further complication is that the adhesive not in contact with the backsheet will not transfer from the release paper making use of the absorbent article more difficult, as the release paper can now stick to unwanted surfaces, complicating attachment of the absorbent article. In addition direct application of an adhesive to the backsheet, will not apply adhesive to the valleys formed in the backsheet resulting in the same problems with the release paper.
A method of forming deep channel embossments is needed that prevents damage to the backsheet of the absorbent article, provides a substantially consistent depth to an embossment region, and allows for proper adherence of the release paper to the backsheet.